Why is my player falling through the terrain?

I imported a character from Mixamo, created a terrain, added rigidbody to the terrain and checked IsKinematics, added rigibody and character control to the player. And still, the Player falls through the ground. I also tried adding box collider to the terrain but it didn't help.

I have just started learning Unity and stuck here for the whole day. Please help.

Note: the player is well above the terrain and not intersecting at the time of execution.